1. Field of the Invention
The present invention relates generally to medical methods and kits. More particularly, the present invention relates to methods and kits for flushing an interior lumen of an implanted catheter prior to closing the catheter between successive uses.
Implanted catheters enjoy widespread use in a number of medical procedures. For example, intravenous (IV) therapy relies on long-term implantation of a venous catheter to deliver fluids, medications, and other substances to a patient. Hemodialysis and hemofiltration both rely on separate draw and return catheters implanted in a vein to allow extra corporeal treatment of the blood. Peritoneal dialysis, in contrast, relies on a single catheter implanted in the peritoneum to permit introduction and withdrawal of dialysate to permit in situ dialysis.
The need to leave catheters implanted over long periods of time raises a number of concerns. For example, the catheters can become infected requiring treatment of the patient and often times removal of the catheter. This is a particular problem with transcutaneous catheters where the skin penetration is a common route of infection. Secondly, implanted catheters can often become plugged or fouled over time. This is a particular problem with intravascular catheters where clotting and thrombus formation within the catheter lumen can be problematic.
To reduce problems associated with thrombus formation, it is now common to xe2x80x9clockxe2x80x9d intravascular access catheters between successive uses. Locking typically involves first flushing the catheter with saline to remove blood and other substances from the catheter lumen. After the catheter has been flushed, an anti-coagulant solution, typically heparin, is then injected to displace the saline and fill the lumen. The heparin-locking solution both excludes blood from the lumen and actively inhibits clotting and thrombus formation within the lumen. While some thrombus may still form at the distal tip of the catheter, the formation is usually minimal and presents few problems. It has further been proposed to combine various anti-microbial substances with the locking solution in order to inhibit infection at the same time that thrombus is being inhibited.
While generally effective, the use of heparin locks suffers from a number of disadvantages. The need to prepare a heparin solution at the end of every catheter treatment session is time-consuming and presents an opportunity caregiver for error. Hemodialysis and hemofiltration patients will have to undergo such heparin locks at least several times a week, while patients on IV may have to undergo such heparin locks several times a day. Over time, the inconvenience and expense of performing heparin locks can build up. Moreover, the need to combine a separate anti-microbial agent in the heparin lock solution further complicates the procedure and adds expense, and the addition of an anti-microbial agent to the heparin lock will generally be effective only within the lumen and at the openings from the lumen. There will be little reduction in the risk of infection in the regions surrounding the implanted catheter, including at the point of penetration through the skin where the risk of infection is the greatest.
For all these reasons, it would be desirable to provide improved methods and kits for locking implanted catheters between successive uses. Such locking methods should inhibit fouling of the catheter lumens and/or reduce the chance of infection, preferably both. In particular, such methods and kits should be easy to implement, require minimum or no preparation, be of low cost, and be useful with most or all types of implanted catheters, including hemodialysis and hemofiltration catheters, IV catheters, peritoneal dialysis catheters, and the like. At least some of these objectives will met by the inventions described hereinafter.
2. Description of the Background Art
U.S. Pat. No. 4,929,242, describes a solution containing glycerol and having a density similar to that of blood for providing a heparin lock on an intravenous catheter. U.S. Pat. No. 5,077,281 describes an anti-microbial solution containing a taurolin compound for inhibiting coagulation in dialysis catheters and other vascular prostheses. Commonly assigned U.S. Pat. No. 5,807,356, and copending application Ser. Nos. 08/856,641; 08/896,592; 08/896,790; 08/896,791; 08/942,990; 09/003,772; 09/161,044; 09/161,068; and 09/248,156, are relevant to the present application. All of the above patents and pending applications are incorporated herein by reference.
The present invention provides methods and kits for the improved locking and/or disinfection of subcutaneously and transcutaneously implanted catheters. The catheters typically will have a distal end which is open to a body lumen. Most commonly, the catheters will be intravascular catheters where the distal end is implanted in or attached to a blood vessel, usually a vein, but in some cases an artery. Exemplary intravascular catheters include hemodialysis and hemofiltration catheters, intravenous catheters, and the like. Intravenous catheters can be used for a wide variety of purposes, including fluid infusion, drug delivery, and the like. Catheters attached other than to the vasculature include peritoneal dialysis catheters which are open to the peritoneal cavity, and the like.
The catheters which are treated by the methods of the present invention may be transcutaneously implanted or subcutaneously implanted. By xe2x80x9ctranscutaneously implanted,xe2x80x9d it is meant that the distal end of the catheter is attached to or implanted within a target body lumen and a proximal end of the catheter is located externally to the patient. An intermediate portion of the catheter will thus pass through or penetrate the patient""s skin, and the proximal end of the catheter will usually have a hub to permit selective attachment of infusion tubes, syringes, solution bags, and the like. Most commonly, the proximal attachment hub will have a luer fitting. By xe2x80x9csubcutaneously implanted,xe2x80x9d it is meant that the entire catheter is implanted beneath the skin and no portion of the catheter extends through the skin. Such subcutaneously implanted catheters are typically attached to a fully implanted hub at their proximal ends. The hub permits percutaneous access via a needle or other penetrating element. After a treatment session is finished, the needle or other penetrating element is removed and all portions of the catheter and proximal hub are then located beneath the skin. Examples of such subcutaneously implanted catheters and proximal access hubs are described in the commonly assigned, copending applications described above, as well as U.S. Pat. No. 5,807,356, the full disclosures of which have previously been incorporated herein by reference.
As described in the Background section above, both transcutaneously and subcutaneously implanted catheters are subject to fouling and plugging, particularly in and about their distal ends which are implanted in or attached to a blood vessel or other body lumen. To reduce the risk of such fouling, the present invention provides and methods and kits for filling a lumen of the implanted catheter with a lower alcohol, typically ethanol, propanol, or butanol, preferably isopropanol. Surprisingly, it has been found that these lower alcohols are effective in inhibiting fouling and plugging of the lumen, particularly in inhibiting clot formation within the lumens of intravascular catheters. The ability to inhibit clot formation without the need to prepare and use heparin solutions is a significant advantage. Moreover, the lower alcohols have the additional ability to inhibit infection without the need to incorporate any additional active agents or materials. Thus, both the reduction of catheter fouling and the inhibition of infection can be achieved with the use of a commonly available, widely accepted material which is introduced to the catheter lumen in a convenient fashion, as described in more detail below.
The ability to inhibit or prevent infection of the implanted catheter can be improved by utilizing catheters where at least a portion of the catheter body is sufficiently porous to allow the lower alcohol or other disinfecting material to permeate the catheter body and, preferably, pass outwardly into the tissue region surrounding the catheter. While the use of such porous or partially porous catheter bodies can be beneficial with many anti-microbial locking solutions, such as that taught in U.S. Pat. No. 5,077,281, the full disclosure of which has been incorporated herein by reference, it is particularly useful with the lower alcohols of the present invention. It will be appreciated that the lower alcohols have relatively low molecular weights and polar structures which will enable them to readily penetrate into and optionally through many porous materials. Exemplary porous materials for construction of the catheter body include silicone rubber, expanded PTFE (e.g., GORE-TEX(copyright), medical membranes) and the like. Such materials may be formed into the tabular catheter bodies or may be incorporated as separate component(s) into the catheter bodies.
In a first aspect, methods according to the present invention for locking an implanted catheter comprise filling a lumen of the catheter with a lower alcohol, where the lumen is open to a body lumen, typically a blood vessel, the peritoneum, or the like. The lower alcohol is selected from the group consisting of ethanol, propanol, and butanol, with the presently preferred alcohol being isopropanol. The lower alcohol may be pure, but will more usually be in aqueous solution, typically at 1% to 100% by volume, usually from 50% to 100% by volume. The implanted catheter may be a transcutaneous catheter attached at its distal end to the blood vessel, the peritoneal cavity, or the like. Alternatively, the implanted catheter may be a subcutaneously implanted catheter which is attached at its distal end to a blood vessel, the peritoneal cavity, or the like.
In a second aspect, a method according to the present invention for disinfecting an implanted catheter comprises introducing an anti-microbial solution into a lumen catheter, wherein at least a portion of the catheter is sufficiently porous to permit diffusion of the anti-microbial solution outwardly from the lumen into the catheter body, and preferably into tissue surrounding the catheter to inhibit or prevent infection. Exemplary and preferred anti-microbial solutions include lower alcohols, preferably ethanol, propanol, or butanol, and most preferably isopropanol, as described above. The implanted catheters may be subcutaneously or transcutaneously implanted.
In a third aspect of the present invention, a kit for locking an implanted catheter comprises a container (optionally a syringe) holding a volume of a lower alcohol and instructions for use setting forth a method comprising filing a lumen of the catheter with the lower alcohol. The kit may further comprise a package for holding both the container and the instructions for use, such as a box, tray, tube, pouch, or the like. The lower alcohol is typically selected from the group consisting of ethanol, propanol, and butanol, preferably being isopropanol. The volume of lower alcohol in the container is typically in the range from 1 ml to 20 ml, preferably from 2 ml to 10 ml, usually being about 2 ml to 4 ml. Additionally, the container will usually comprise a syringe to permit direct introduction of the lower alcohol into the implanted catheter.